Apparatus for sherardizing articles.



H. C. HARRISON.

APPARATUS FOR SHERARDIZING ARTICLES.

APPLICATION FILED AUG.31, I916.

Patented Jan. 21, 1919.

2 SHEETSSHEETI -V\ E mi u i \m b 3 Moe/H01, fl 611120715021 by H. C. HARRISON.

APPARATUS FOR SHERARDIZING ARTICLES.

APPLICATlON FILED AUG.3, 916.

UNITED OFFICE.

HERBERT CHAMPION HARRISON, OF LOGKPOB'I, NEW YORK;

APPARATUS FOR SHERARDIZING ARTICLES.

Specification of Letters Patent.

Patented Jan. 21, 1919.

Original application flied June 19, 1916, Serial No. 104,520. Divided and this application filed August 81, 1916. Serial No. 117,942.

To all whom it may concern:

Be it known that I, HERBERT CHAMPION HARRISON, a subject of the King of Great Britain, residing at Lockport, in the county of Niagara and State of New York, have invented certain new and useful Improvements in Apparatus for Sherardizing Articles; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

- This invention relates to an apparatus for roducing sherardized articles of metal and has for its object to provide an apparatus of this character which will be slmple in construction, more eflicient in operation and less costly than those heretofore proposed.

With these and other objects in view the invention consists in the novel details of construction and combinations of parts more fully hereinafter disclosed and particularly pointed out in the claims.

The apparatus forming the subject of this invention is capable of wide use, but is espe cially adapted for carrying out the process and producing the articles described and claimed in my copending application, filed June 19, 1916, Ser. No. 104,520, and entitled Method of sherardizin articles, of which this application isa ivision, and also in my application filed Apr. 11, 1916, Ser. No.

v 90384, and entitled Process of sherardizing strips for making automobile radiator cores.

Referring to the accompanying drawings, forming a part of this specification in which like numerals designate like parts in all the views Figure 1 is a partly sectional plan view of a portion of an apparatus made in accordance with this invention;

Fig. 2 is an elevational view partly in section of that portion of the apparatus illustrated in Fi 1;

Fig. 3 is a pliin view of the remainder of the apparatus illustrated in Fig. 1;

Fig. 4 is an elevational view of the remainder of the apparatus illustrated in Fig. 2;

Fig. 5 is a transverse sectional view of the apparatus taken on the line 5--5 of Fig. 1;

Fig. 6 is a diagrammatic view illustrating a conventional air of reducing rolls;

' Fig. 7 is a diagrammatic sectional view on an exaggerated scale showing a portion of apartly finished plate, sheet or wire; and

Fig. 8 is a view slmilar to Fig. 7 showing a portion of the finished article.

1 indicates a roll of thin sheet material, such for example as thin sheet steel or wire. This roll is fed into the end 2 of the trough 3 which is conveniently filled with zinc dust 4 or other sherardizing mixture, for a space of say about two feet or up to the end 5 of the middle trough 6. In the case of a strip I find it desirable to send it through the apparatus on edge, or occupying a vertical plane as illustrated, because this disposition of the strip lessens friction through the zinc dust.

I also find that it is desirable to have a considerable thickness of zinc dust all' around the strip or wire 7 as indicated, not only to exclude air, but also to aid in maintaining a constant quantity of zinc or other metal in the reaction zone; in ractice the troughs 3 and 6 can convenient iy be made of say four inches or more in cross section each way, with the strip or wire 7 occupying their center as illustrated. At 8 the trough may be divided as by an' asbestos diaphragm, or partition through which the strip or wire passes into the sherardizing portion or trough 6, to the hottest zone 9. This said trough 6 may he say from six feet to twelve feet in len h, and it may conveniently be divided oif y an asbestos partition 10 from the third trough 11 constituting the cooling zone of the apparatus. The said trough or portion 11 may be say about six feet or eight feet long or longer, and may likewise be of the same cross section as the other portions or troughs 3 and 6 of the apparatus.

The apparatus is conveniently provided in its heated portion or sherardizmg zone with the inclined deflecting plates 12 which have the effect of constantly forcing down and renewing the fresh material in contact with the traveling strip or other wire 7, and

thereby insuring that zinc dust of a constant or wire 7 and to pull it through the ap-' paratus. In ractice said means may consist of a suita 1e motor operating a winding drum not shown. 14 represents any suitable H; lb

support for the troughs 3, 6 and 11, in this instance shown as brick work; and 16 any suitable means of heating the trough 6 an raising the sherardizin zone to the desired temperature. In this mstancc the heating means is a plurality of gas burners the openings for which are also indlcated at 17, but electrical heating means (not shown) may be employed in any suitable manner, and in large scale operations is to be preferred to the means 16 for many articles.

18 represents a pyrometer it IS convenlent to employ in order that the temperature may be known at all times. 20 represents any suitable connection preferably a hopper extending from one end. of the trough 6 to the other for supplying fresh zinc or other sherardizing powder to the sherardizing zone, and thus preventing the said powder from becoming exhausted.

It is recommended that the temperatures on each side of the middle zone 9 of the trough 6 be gradually diminished as by re 'ulating the burners.

he art of sherardizing metal is now well known, and its advantages and disadvantages are familiar to those skilled in the art.

Among the advantages is the ability for many purposes to deeply penetrate a plate,

rod, bar or billet with a true alloy of the metal being sherardized, with the metal or metals employed as a protective coating. Further, the richness of this alloy in the coating material gradually decreases as the interior .of the metal being coated is reached, so it is practically impossible in most cases to flake it ofi, or to mechanically remove said coating, no matter how rough the treatment the article may receive.

Among the very serious disadvantages of the sherardizing process for thin plates, small wires, etc., 1s the fact that the said alloy is usually more brittle than the use of said articles will stand, and therefore, when such use demands ductility, for example, in the finished sherardized article, it is found, at least in the case of thin plates and small wires, that said finished articles are so brittle as to be worthless for many purposes to which they would otherwise be put.

Upon an examination of the physical and chemical structure of such articles, it is found that this objectionable brittleness is due to the sherardizing coating being rela- -tive1y of such a mass or body and having penetrated so far into the body of the metal, that the brittle alloy formed has replaced sufiicient of the origmal material to render the metal too brittle for use.

It is further found that owing to the method of carrying out the sherardizing process as heretofore practiced, it is impossible to commercially coat articles of such small cross sections as steel plates that are suitable for making cans, automobile radiamenses poses. Onereason for this, is the inability of the operator by known methods to effectively coat all parts of the article and at the same time accurately regulate the penetration of the coating or the body of the mass of the coating alloy within the narrow limits demanded.

According to my method now to be disclosed, I take aplate, a wire or other article, of a greater thickness than that desired in the finished article, and coat it -at a definite redetermined temperature with a sherardizmg mixture of a predetermined definite composition or concentration of the coating metal, and for a definite predetermined time, and thus regulate the penetration of the body of the coating mass or quantity of the applied metal. I therefore produce a partly finished article of a predetermined ductility, depending upon the particular regulation of the temperature, time and concentration that is had during the process, and with a coating thicker than that designed in the finished article.

Now as the said coating is so intimately bound to the original coated metal, I can, without injury thereto, subject the coated and partially finished article to a compressing action, such for example, as a rolling or -a drawing process in order to reduce "its cross section to the desired dimensions.

In the case of plates, I may subject the original plate having a thickness of say twice as great as is desired in the finished plate to the. sherardizing process, and then by passing the same through rollers after being sherardized, I may double the surface of said plate in reducing its thickness to one half, and thus so redistribute the sherardized coating over its surfaces as to effectually prevent oxidation, while at the same time, preserving suflicient of the original ductility as will enable the coated plate to be used for its intended purpose. In the case of wire, substantially the same procedure is had, but of course, a drawing process is generally substituted for the rolling process. But in both cases, since the quantity and penetration of the coating material can be roughly controlled if the old sherardizing process is employed, and can be accurately controlled if a continuous process is employed, and since the surface over which it is to be later spread can always be accurately controlled during the In most cases I prefer to employ the well known commercial sherardizing mixture composed of finely divided zinc oxid; but 0 course, other suitable well known mixtures, such as those containing zinc and aluminum, zinc and copper, zinc and tin, etc., may be employed when desired.

For some purposes, I find that the compacting action of the rolling and drawing processes improves the physical properties of the coating, and in that the latter is rendered smoother and probably less porous, and. therefore, more resistant to oxidizing actions.

A convenient method of carrying out the sherardizingprocess is to continuously pass at a predetermined speed, the plate, strip,

'wire or other article, through a sherardizing zone, containin a mixture of a predetermined composition, while maintaining constant a predetermined temperature of the zone and a predetermined concentration of free metal in the mixture, all as is illustrated in the drawings- I have discovered that the quality or character of the sherardized coating depends upon three variables :-the time the metal is exposed to the sherardizing reaction, the

' temperature at which it is exposed, and the concentration of free coating metal in the sherardlzing mixture.

In a contlnuous process, such as one involving the continuous moving of a wire or strip through the sherardizing zone, the time of exposure can be accurately controlled by controlling the speed, so that the latter affords a convenient means of ultimately con trolling the ductility of the finished articles after the other two variables have been settled upon.

That is to say, at a given constant temperature and concentration, difl'erent s eeds will determine to a large extent, the epth the main body portion or mass of the coating will penetrate into'the body of the article being coated, as well as the character or thickness of said coating, all as will now appear.

For example, the sherardizing reaction will take place more energetically the higher the temperature, and at least some portions of the coating will'penetrate more deeply as the temperature rises. But if the concentration of zinc for example is too high for a given temperature the powder will cake, and the coating will come out irregular and smeared. Therefore, as the temperature is increased the concentration should be kept below the point at which caking or smearing occurs, especially if zinc alone is used for the coating. In general the higher the temperature the better, so long as a coating of the desired thickness and quality is obtained, but practical limits are reached due to the softening and loss of tensile strength of the strip or wire being pulled through the ap aratus. 4

ood working temperatures for zinc coatings are from say 1000 F., to 1.400 F., good workin concentrations are from say 20% to 40% zinc, and good working speeds of the strip or wire throu h the apparatus are from say ten feet to thirty feet per minute, all depending upon the particular results desired. 'Small articles are conveniently attached to a chain, strip or wire and pulled through-the sherardizing zone.

After the plate, strip, wire or other article has been treated as above described, it is subjected to a reducing action in rolls, or dies, and its cross section brought down to the required dimensions, whereupon it is found to have an exceedingly coherent and resistant coating, as well as a ductile body portion. Fig. 6 diagrammaticall illustrates a strip, plate or wire 30 passing between the rolls 31, Fig. 7 illustrates said article 30 and its coatin 35 before being subjected to the rolls, whi e Fig. 8 shows the core and coating of said article greatly reduced in cross section after passing through said rolls.

Such coated plates, strips, wires, etc., may be readily substituted for many purposes for which brass and copper is now-used.

The drawing or rollin process is facilitated in the case of stee by the fact that the strip or wireenters the trough 3 cold, and after leaving the hottest zone 9, it gradually cools until it leaves the trough 11 cold or substantially so. In other words, the continuous process automatically anneals the metal. i

The troughs being packed with the same mixture no contamination occurs due to the contents of the one trough being drawn into another trough while the packing material of troughs 3 and 11 further serve as eflt'ectual air seals to prevent the steel from being oxidized before and after the sherardizing action.

While it is'preferred to employ a process of continuously passing the articles through a sherardizing zone in the manner illustrated, yet it is not essential to do so in the case of small articles having a comparatively large cross section, such for example, as bolts, nails, screws, etc., for such articles as these can be treated in bulk in drums by the present process and then subjected to dies or other mechanism in order to reduce them to the required dimensions.

It is also apparent that the articles may be given two or more separate sherardizing coatings of difi'erent metals when desired. For example, the articles may have separate coatings of zinc and copper, copper and aluminum, etc.

It is obvious that those skilled in the art may vary the details of construction as well as the arrangement of parts without departing from the spirit of the invention and therefore I do not wish to belnmted to the above disclosure except as may be required by the claims.

What I claim is 1. In an ap aratus for continuously sherardizing artlc es of small cross section and great length the combination of an elongated chamber containing an air seal of substantially cold sherar izmg powder; a second elongated chamber containing a coat ing sherardlzing powder; a third elongated chamber containing an air seal of substantially cold sherardizing powder adapted to gradually reduce the temperature of said articles after the sherardizing reaction; a hopper above said second chamber adapted to continuously furnish fresh powder thereto; means for continuously passing said articles through said chambers; and means for raising the said articles to a predetermined sherardizing temperature while in said second chamber.

2. In an apparatus for continuously sherardizing articles of small cross section and great length the combination of an elongated chamber containing an air seal of zinc dust; a second elongated chamber of comparatively great depth insulated from said first chamber and containing a coating zinc dust; a third elongated chamber insulated from said second chamber and containing an air seal of zinc dust; means comprising bafiles in said second chamber for insuring a constant supply of fresh zinc dust to the surfaces of the articles to be coated;

means for continuously passing said articles throu h said chambers; and means for raising the said articles to a predetermined sherardizing temperature while in said second chamber, substantially as described.

3. In an apparatus for continuously sherardizing articles of small cross section and great length the combination of an elongated chamber containing an air seal of substantially cold zinc dust; a supply drum mounted on said chamber; a second elongated chamber of comparatively great depth containing a coating zinc dust, insulated from said first chamber; a third elongated chamber containing an air seal of substantially cold zinc dust adapted to gradually reduce means comprising inclined deflecting plates in said second chamber for insuring a constant supply of fresh zinc dust to the surfaces to be coated; means for raising the said articles to a redetermined sherardizing temperature w ile in said second chamber; a receiving drum mounted on said third chamber; and means for rotating said receiving drum at a constant speed, substantially as described. I

4. In an apparatus for continuously sherardizing articles of small cross section and great length the combination of an elongated chamber containing a coating sherardizing powder; a pair of chambers located one at each end of said first chamber, each containing an air seal of substantially cold sherardizing powder; means for continuously passing said articles through said chambers; means for raising the contents of said first chamber to a predetermined sherardizing temperature; and means for preventing the powder in saidpair of chambers from becoming heated and contaminated with the powder from said first chamber, substantially as described.

5. In an apparatus for continuously sherardzing articles of small cross section and great length the combination of an elongated chamber containing a coating zinc dust; a pair of chambers located one at each end of said first chamber and in alinement therewith, each containing an air seal of substantially cold zinc dust; means for continuously passing said articles through said chambers; means for raising the contents of said first chamber to a predetermined sherar'dizing temperature; and perforated insulating means between adjacent chambers for preventing the zinc dust in said pair of chambers from becoming heated while permitting said articles to pass therethro'ugh, substantially as described.

In testimony whereof I afiix my signature in presence of two witnesses.

HERBERT CHAMPION HARRISON. Witnesses:

HARRIET I-IUs'roN, an F. Covnn'r.

bit 

